The overall objective of this project will continue to be to gain knowledge of the ecology of arboviruses sufficient to allow effective disease control programs. This will be accomplished by pursuit of seven immediate objectives. To determine the biological and physical traits of mosquito vectors that control their competence as vectors of arboviruses. To evaluate variations in the vector competence of geographically representative collections of field populations of primary vectors of arboviruses. To elucidate alternative methods by which arboviruses overwinter in a temperate area. To evaluate the feasibility of inserting genetically modified mosquito populations into the field to control the numbers and vector competence of natural populations. To extend the knowledge of the biology of disease vectors. To develop statistical models that express the variables that control vector populations and associated viral transmission cycles. To characterize new arboviruses and determine their relationship to human and equine disease.